Any TopSpice Users Here?

Started by Jim Thompson in sci.electronics.design6 years ago 3 replies

Any TopSpice Users Here? I have an OpAmp model out there that runs fine on PSpice, LTspice, HSpice, etc., but balks on TopSpice. The error...

Any TopSpice Users Here? I have an OpAmp model out there that runs fine on PSpice, LTspice, HSpice, etc., but balks on TopSpice. The error report, from the TopSpice output file is: GSw_Sw3 N_22 -VB VALUE {((TANH(9.485/0.1*(V(SHUTDOWN, + GND)-0.5))+1)/2)*(V(N_22, -VB)/1)} 0*ERROR*: mismatched parentheses in above expression check result= -1 0*ERROR*: loading VALUE be...


5-volt tolerant CMOS

Started by John Larkin in sci.electronics.design8 years ago 38 replies

Lots of CMOS gates and such are tolerant of pin voltages above Vcc, typically rated for 7 volts max. Does anybody know what sort of input...

Lots of CMOS gates and such are tolerant of pin voltages above Vcc, typically rated for 7 volts max. Does anybody know what sort of input circuits are typically used? Does it behave like a zener? To ground? Some parts specify an allowed input curent in the pullup direction, some don't. I'm designing a really tiny board, and an opamp can potentially overdrive an analog mux, an FSA3157....


phase shift in inverting opamp

Started by John Larkin in sci.electronics.design4 years ago 22 replies

I need an instrument input amp with 1M input impedance and -0.5 gain, and very low phase shift out to 100 KHz. I'm not sure what sorts of...

I need an instrument input amp with 1M input impedance and -0.5 gain, and very low phase shift out to 100 KHz. I'm not sure what sorts of parasitic shunt capacitance I'll see on the resistors, theoretically 1M input and 500K feedback. My board stackup may affect the shunt capacitances some. Maybe if I use 2x500K instead of 1M, things will work out automatically. Good news: my preferr...


Quantization and sample/hold in spice

Started by Klaus Kragelund in sci.electronics.design4 years ago 19 replies

Hi I need to introduce and error in a signal, both quantization and sample/hold Sofar I have done it by placing an opamp based sample/hold...

Hi I need to introduce and error in a signal, both quantization and sample/hold Sofar I have done it by placing an opamp based sample/hold followed by a 8bit ADC (ADC8break) and a 8 bit DAC (DAC8break) But it doesn't feel right to use that much circuitry just to simulate an error in the system Anyone know if it can be done with ABM blocks? (sample and hold can be done with a zero order...


Common Mode Input Voltage

Started by panfilero in sci.electronics.design8 years ago 6 replies

I think this is right but wanted to make sure I'm looking at the LM321 OpAmp It says it has an input common-mode voltage range of V+ -...

I think this is right but wanted to make sure I'm looking at the LM321 OpAmp It says it has an input common-mode voltage range of V+ - 1.5 page 3 of this datasheet http://www.ti.com/lit/ds/symlink/lm321.pdf I'm thinking that means that if I run this off a single supply of 5V and us= e it as a buffer, that I will be limited to an max input voltage of 3.5V, a= nd that if I go over, I ...


Power opamp.. output "near" the rails.

Started by George Herold in sci.electronics.design6 years ago 13 replies

Hi all, browsing power opamps at DK. I need something with at least 300mA of output current at least +/- 5V power supplies, and with an output...

Hi all, browsing power opamps at DK. I need something with at least 300mA of output current at least +/- 5V power supplies, and with an output that will get within a volt of the rails. I've used the rail-rail opa569, but not enough voltage. The OPA561 looks like it would work... "not recommended for new designs". http://www.ti.com/lit/ds/symlink/opa561.pdf replaced with the opa564, h...


Current reference REF200

Started by George Herold in sci.electronics.design6 years ago 9 replies

Hi all, I'm taking over someone's circuit. The schematic has an REF200 in it. I'd never seen this IC before. Two sources and a current...

Hi all, I'm taking over someone's circuit. The schematic has an REF200 in it. I'd never seen this IC before. Two sources and a current mirror. http://www.ti.com/lit/ds/symlink/ref200.pdf In this schematic the current sources are just turned into voltages. (by passing through a TIA opamp circuit.) I'm thinking of pitching the whole thing and using some nice voltage references to start w...


Thermistor pressure sensor

Started by George Herold in sci.electronics.design8 years ago 24 replies

Thermistor pressure sensor. Here's a circuit for using a thermistor as pressure sensor. https://www.dropbox.com/s/wyekkczkvs1dm32/tcbr.jpg from...

Thermistor pressure sensor. Here's a circuit for using a thermistor as pressure sensor. https://www.dropbox.com/s/wyekkczkvs1dm32/tcbr.jpg from here, http://www3.telus.net/schmaus2/vacf/index.html It's like a pirani gauge in that you measure how much voltage you need to keep the element at a constant temperature. I don't like the sorta open loop opamp. Maybe an instrument amp? I was fi...


alternate active all-pass

Started by John Larkin in sci.electronics.design3 years ago 27 replies

The classic opamp all-pass is in Williams 3, https://www.dropbox.com/s/nhevg979w7gtxib/90_degree.JPG?dl=0 We're doing that but see some...

The classic opamp all-pass is in Williams 3, https://www.dropbox.com/s/nhevg979w7gtxib/90_degree.JPG?dl=0 We're doing that but see some harmonic distortion at high frequency, above 8 MHz in our case. This circuit inverts at low frequencies and has unity gain at high frequency. Opamps have bad CMRR at high frequencies, which is why Jim Williams said "always invert." There could also ...


TIA-PD compensation, by eye

Started by George Herold in sci.electronics.design4 years ago 81 replies

Hi all, months ago I bought this screaming fet opamp (THS463) to gin up an old photodiode circuit. Put it in today, and the step response doesn't...

Hi all, months ago I bought this screaming fet opamp (THS463) to gin up an old photodiode circuit. Put it in today, and the step response doesn't look right. Here's 1 k ohm of gain w/ 10 pF across it. https://www.dropbox.com/s/ncswyuokm9hktb5/step-10pF.BMP?dl=0 A lot of wiggles, but the amplitude isn't big enough. Here's the uncompensated step. https://www.dropbox.com/s/rilf9gvmlwldaj...


Stepped sine wave

Started by George Herold in sci.electronics.design10 years ago 92 replies

This is a continuation of the 50kHz VCO thread I started last week. I tried the stepped sine wave idea as suggested by James A, and...

This is a continuation of the 50kHz VCO thread I started last week. I tried the stepped sine wave idea as suggested by James A, and Phil H. The circuit clocks a MC14017 at 10x(F) to make a stepped sine wave at frequency (F). The ten outputs from the 4017 are sent through appropriate resistors and into the summing junction of an opamp. Here=92s a =91scope shot of the stepped output overlaid...


Textbook recommendation

Started by o pere o in sci.electronics.design9 years ago 46 replies

So imagine undergraduate students who have studied: - 2 semesters of digital design (from gates to VHDL to a small processor) - 2 semesters of...

So imagine undergraduate students who have studied: - 2 semesters of digital design (from gates to VHDL to a small processor) - 2 semesters of circuit theory (from Kirchoff to OpAmp, Laplace, Fourier, Bode) - 2 semesters of analog and digital signals and systems (Modulations, sampling, DSP) - 1 semester of analog electronics - 1 semester of RF circuits - 2 semesters of high level progr...


4 ghz opamp

Started by John Larkin in sci.electronics.design7 years ago 10 replies

This is interesting: 4 GHz and CMOS inputs. http://www.linear.com/product/LTC6268-10 http://www.linear.com/docs/46371 What's amazing is...

This is interesting: 4 GHz and CMOS inputs. http://www.linear.com/product/LTC6268-10 http://www.linear.com/docs/46371 What's amazing is that it's available as a dual. Looks like they just dice up two amps in one chunk and package that. Slew rate is sorta low, so it's not good for high-swing stuff. The schematic on data sheet page 11 is interesting. -- John Larkin ...


ADA4522 opamp hangup

Started by John Larkin in sci.electronics.design3 years ago 47 replies

ADA4522 is an amazing amp. 55 volt supplies, low noise, 5 uV max offset, EMI hardened, pA bias current. But it has a hangup mode as a follower:...

ADA4522 is an amazing amp. 55 volt supplies, low noise, 5 uV max offset, EMI hardened, pA bias current. But it has a hangup mode as a follower: if the output goes to V+ the input back-to-back diodes keep both inputs above the legal common-mode range. Pity it's not RRIO. Similar amps from TI and Maxim seem to have the same issue. Here's one fix: https://www.dropbox.com/s/tdzs1ydi7quzbs7...


noise in LT Spice

Started by John Larkin in sci.electronics.design11 years ago 52 replies

I'm wanting to simulate noise in a TIA. It will use a discrete jfet at the input, then opamps. Check me out on this, please: I assume...

I'm wanting to simulate noise in a TIA. It will use a discrete jfet at the input, then opamps. Check me out on this, please: I assume the jfet models have built-in gate equivalent noise voltages and currents, somewhere in the model string. Also assume the the LTC opamp models include noise params. Ditto Johnson noise in all resistors. The LT Spice help pdf file says that.....


48V microphone phantom voltage problem

Started by N_Cook in sci.electronics.design8 years ago 15 replies

Repairing a commercial digital audio processor unit , working ok until someone turned on the phantom voltage while in use, now bad white-noise...

Repairing a commercial digital audio processor unit , working ok until someone turned on the phantom voltage while in use, now bad white-noise intrusion introduced at the first opamp. As it happens , ironically, no fancy expensive DC powered mics used as the input. The 48V is "blocked" from an NJM2122 low noise op-amp by 63V 33uF electro and 10K . But of course switching on the 48V transf...


voltage regulator

Started by John Larkin in sci.electronics.design7 years ago 17 replies

Here's a little programmable voltage regulator to go with that 1200 volt power supply that I posted somewhere above. The R4-D2-G1-D1 mess...

Here's a little programmable voltage regulator to go with that 1200 volt power supply that I posted somewhere above. The R4-D2-G1-D1 mess approximates a Hitachi photovoltaic optocoupler. It's possible that not everyone has the "universal opamp" in their LT Spice. We've had that problem recently. Version 4 SHEET 1 880 796 WIRE 304 -272 224 -272 WIRE 432 -272 304 -272 WIRE 43...


poor op-amp settling time

Started by Winfield Hill in sci.electronics.design2 years ago 17 replies

I selected a Maxim MAX4239 opamp for a low-power design project, for its 2.5uV offset, its Iq = 0.6mA, and for G> 10, its 6.5MHz GBW. For...

I selected a Maxim MAX4239 opamp for a low-power design project, for its 2.5uV offset, its Iq = 0.6mA, and for G> 10, its 6.5MHz GBW. For G=10, that's a 650kHz -3dB bandwidth. Slew 1.6V/us. Response, t = 1/pi 650kHz = 0.5us. But the datasheet's 0.1% settling time spec is 500us, 1000x times slower! Makes little sense. Sad. Dunno whether to believe a very poor datasheet number.


State variable filter Q

Started by Robert Baer in sci.electronics.design6 years ago 14 replies

This is a multi-part message in MIME format. --------------040708060307040005060400 Content-Type: text/plain; charset=ISO-8859-1;...

This is a multi-part message in MIME format. --------------040708060307040005060400 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Just discovered state variable filters, look as a good way to get sharp filtering. BUT. Theory looks super, Spice modelling (with "opamp" chosen) is so-so, and hell to tune and hell to get a nice peak. ...


low-cost opamps in sot-23

Started by Winfield Hill in sci.electronics.design2 years ago 8 replies

I have received a respectable 2SK3018 MOSFET, made by Jiangsu Changjiang, from LCSC, only $0.0133 each. Now I'm looking for a low-cost ...

I have received a respectable 2SK3018 MOSFET, made by Jiangsu Changjiang, from LCSC, only $0.0133 each. Now I'm looking for a low-cost opamp to go with it. Found the TP09, a 6MHz dual, from 3Peak, Vos 400uV, $0.06 each, looks fine, but would like a single type in a SOT-23 package. Picky, picky, picky! Ah, the LMV321 in SOT-23-5, in stock at LCSC: TI: $0.0735, Diodes: $0.077,...