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Hi,
The circuit of common source amplifier is attached. ckt4 is amplifier with no source bypass capacitor. In ckt5 the source bypass capacitor c2 is added. The ckt5 shows some strange output (50 Hz modulation present). The amplifier is biased with a battery. The measurements are the output...
I had done some measurements where the transistor saturates at Vds> 100 mV. My Vds is 170 mV approx. Similar characteristics were observed in the cryogenic environment as well.
Reg power supply filtering, do RF beads help? I am also planning to add 100 nF parallel to the 100 pF in the power...
Removal of preamp power stops interference. Interference is present when it is powered on. Also having a input termination resistor (across the input LC tank circuit) doesnot make any difference. The interference is still present.
The choice of the operating point takes into consideration the...
Hi,
I am attaching the correct circuit diagram and layout files. The amplifier (common source amp) is mounted inside an aluminium box (see image) and everything is enclosed by a faraday cage to minimize interference.
Should I have extra capacitor for power supply bypass? How do I minimize...
Hi,
I don't know the noise figure of HEMT at 2 MHz. The measurements that I had uploaded were taken at room temperature. I don't really understand why there is no interference when I measure opamp. Interference is only present when HEMT is included in the circuit.
Is the HEMT acting like a...
Hi,
The reason for using HEMT is because of low temperature operability (cryogenic environment) of the device. It is stable. I have checked the spectrum. No signs of oscillation. The operating point is Vds=160 mV, Ids=4 mA
Hi,
I am designing low noise amplifier using HEMT ATF34143. The frequency of operation is around 1-2 MHz. The HEMT is followed by two stages of opamp (OPA847) (Gain=2000).
I would like to measure the total output noise of my amplifiers. I don't see any interference when I measure the noise...
Hi all,
As suggested, I tried removing the resistor in series with the inductor. Now the simulation shows the entire current (1 A) flowing through 63 k at resonance. I guess the resistor in series to the inductor contributes to the loss by decreasing the effective Q.
Hi everyone,
Thanks for your reply. I increased the resolution of my spice (10000 points per decade) and current source changed to 1A. I still find the current through the 68 k resistor less than 500 mA. This is independent of whether I add a resistor in series with the inductor or not. Why...
Hi,
I simulated a simple RLC parallel circuit using LTspice. The circuit diagram and results are attached. A current source (1 nA) connected across parallel RLC. In the AC response, I expect all the current (1nA) to flow through resistor (63 kohms). But I find only 180 pA flowing through the...
I am using a Agilent pHEMT (ATF34143) to be used as an amplifier at lower frequencies (1 MHz) and low temperatures (4 Kelvin). When I try to measure to dc characteristics of the transistor I see osciilations (fosc= 160 MHz) at the drain terminal. I use a bias tee (**broken link removed**)...
Iam usign a GaAs FET (SGM2006). The datasheet says it can be used as UHF LNA.
Iam using it as an voltage amplifier at 1 MHz. I get a frequency response characterstics with voltaage gain of 15 (vout/vin) at 20 kHz and at 1 Mhz voltage gain=2.
The amplifier config is fixed bias common source...
Re: electron spin
Electron donot actually spin (like earth). It just refers to an additional degree of freedom. It is just an additional magnetic moment an electron possess.
Hi,
Iam using sony's 3SK166A dual gate GaAs MESFET to build a cryogenic amplifier. But i have not got a good DC characteristics both at room temperature and Liq helium temperature. Iam attaching the test result corresponding to room temperature. (Gate 2 =0V . no gate leakage)
Please suggest...
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