Could some electronics guru here please clarify this ? The datasheet for the NPN BJT HFA3134(from Renessas Semi.) states: The HFA3134 and HFA3135 are Ultra High Frequency Transistor pairs that are fabricated with Intersil Corporation’s complementary bipolar UHF-1X process. The NPN transistors exhibit an fT of 8.5GHz, while the PNP transistors have an fT of 7GHz. Both types exhibit low noise, making them ideal for high frequency amplifier and mixer applications. Both arrays are matched high frequency transistor pairs. The matching simplifies DC bias problems and it minimizes imbalances in differential amplifier configurations. Their high fT enables the design of UHF amplifiers which exhibit exceptional stability. The datasheet does not provide any S parameter values for any frequency, and I have successfully SPICE modelled common emitter configuration Colpitts oscillators @ 100, 300, 500 and 750 MHz. However, datasheets for other common RF/microwave BJTs such as BFR92A, BFQ67W BFS17 etc, all contain the common emitter S parameters for the respective BJT. So what is so special about the HFA3134 that allows its use at these high frequencies(the stated fT for HFA3134 is 8 GHz), without use of S parameters.Is All hints|suggestions are welcome. Thanks in advance.
Request clarification on BJT HFA3134
Started by ●January 17, 2019
Reply by ●January 17, 20192019-01-17
On 1/17/19 2:27 AM, dakupoto@gmail.com wrote:> Could some electronics guru here please clarify this ? The > datasheet for the NPN BJT HFA3134(from Renessas Semi.) states: > The HFA3134 and HFA3135 are Ultra High Frequency Transistor pairs that are fabricated with Intersil Corporation’s complementary bipolar UHF-1X process. The NPN transistors exhibit an fT of 8.5GHz, while the PNP transistors have > an fT of 7GHz. Both types exhibit low noise, making them ideal for high frequency amplifier and mixer > applications. > > Both arrays are matched high frequency transistor pairs. > The matching simplifies DC bias problems and it minimizes > imbalances in differential amplifier configurations. Their high fT enables the design of UHF amplifiers which exhibit > exceptional stability. > > The datasheet does not provide any S parameter values for > any frequency, and I have successfully SPICE modelled > common emitter configuration Colpitts oscillators @ 100, > 300, 500 and 750 MHz. > > However, datasheets for other common RF/microwave BJTs > such as BFR92A, BFQ67W BFS17 etc, all contain the > common emitter S parameters for the respective BJT. > So what is so special about the HFA3134 that allows its > use at these high frequencies(the stated fT for > HFA3134 is 8 GHz), without use of S parameters.Is > > All hints|suggestions are welcome. Thanks in advance.IIRC the datasheet has a super-detailed SPICE model of both the die and the package parasitics. Cheers Phil Hobbs -- Dr Philip C D Hobbs Principal Consultant ElectroOptical Innovations LLC / Hobbs ElectroOptics Optics, Electro-optics, Photonics, Analog Electronics Briarcliff Manor NY 10510 http://electrooptical.net http://hobbs-eo.com
Reply by ●January 18, 20192019-01-18
On Thursday, January 17, 2019 at 6:27:59 PM UTC+11, daku...@gmail.com wrote:> Could some electronics guru here please clarify this ? The > datasheet for the NPN BJT HFA3134(from Renessas Semi.) states: > The HFA3134 and HFA3135 are Ultra High Frequency Transistor pairs that are fabricated with Intersil Corporation’s complementary bipolar UHF-1X process. The NPN transistors exhibit an fT of 8.5GHz, while the PNP transistors have > an fT of 7GHz. Both types exhibit low noise, making them ideal for high frequency amplifier and mixer > applications. > > Both arrays are matched high frequency transistor pairs. > The matching simplifies DC bias problems and it minimizes > imbalances in differential amplifier configurations. Their high fT enables the design of UHF amplifiers which exhibit > exceptional stability. > > The datasheet does not provide any S parameter values for > any frequency, and I have successfully SPICE modelled > common emitter configuration Colpitts oscillators @ 100, > 300, 500 and 750 MHz. > > However, datasheets for other common RF/microwave BJTs > such as BFR92A, BFQ67W BFS17 etc, all contain the > common emitter S parameters for the respective BJT. > So what is so special about the HFA3134 that allows its > use at these high frequencies(the stated fT for > HFA3134 is 8 GHz), without use of S parameters.Is > > All hints|suggestions are welcome. Thanks in advance.As has been mentioned here before, S-parameters are useful for small signal design at specific bias currents. Their use predates the wide availability of Spice. The HFA3134 and 3135 were introduced relatively recently, and they were never aimed at the kind of market that would run the transistors at a reasonably constant current levels. -- Bill Sloman, Sydney
Reply by ●January 21, 20192019-01-21
On Friday, January 18, 2019 at 6:24:53 AM UTC-5, bill....@ieee.org wrote:> On Thursday, January 17, 2019 at 6:27:59 PM UTC+11, daku...@gmail.com wrote: > > Could some electronics guru here please clarify this ? The > > datasheet for the NPN BJT HFA3134(from Renessas Semi.) states: > > The HFA3134 and HFA3135 are Ultra High Frequency Transistor pairs that are fabricated with Intersil Corporation’s complementary bipolar UHF-1X process. The NPN transistors exhibit an fT of 8.5GHz, while the PNP transistors have > > an fT of 7GHz. Both types exhibit low noise, making them ideal for high frequency amplifier and mixer > > applications. > > > > Both arrays are matched high frequency transistor pairs. > > The matching simplifies DC bias problems and it minimizes > > imbalances in differential amplifier configurations. Their high fT enables the design of UHF amplifiers which exhibit > > exceptional stability. > > > > The datasheet does not provide any S parameter values for > > any frequency, and I have successfully SPICE modelled > > common emitter configuration Colpitts oscillators @ 100, > > 300, 500 and 750 MHz. > > > > However, datasheets for other common RF/microwave BJTs > > such as BFR92A, BFQ67W BFS17 etc, all contain the > > common emitter S parameters for the respective BJT. > > So what is so special about the HFA3134 that allows its > > use at these high frequencies(the stated fT for > > HFA3134 is 8 GHz), without use of S parameters.Is > > > > All hints|suggestions are welcome. Thanks in advance. > > As has been mentioned here before, S-parameters are useful for small signal design at specific bias currents. > > Their use predates the wide availability of Spice. The HFA3134 and 3135 were introduced relatively recently, and they were never aimed at the kind of market that would run the transistors at a reasonably constant current levels. > > -- > Bill Sloman, SydneyThanks for the clarification. I have SPICE modelled common emitter feedback oscillators up to 1000 MHz(1GHz) and 750 MHz common emitter negative resistance oscillator with the HFA3134 (NPN),These simulate very well. However, the HFA3134 performs poorly when configured in the common base|collector modes. Frankly, I do not like manipulating S parameters, and have had to write specialized C code to transform common emitter S parameters(available from manufacturers) to common base S parameters(commonly used for inductive resonators) and so on. The HFA3134 is a very welcome way to avoid this mess.
