Nadya
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Dear all,
I am a first time analogue designer and need help with my Gilbert cell mixer for Bluetooth (CMOS 0.18um technology). The problem is that my circuit has a negative gain though, I believe, 10 dB is achievable. I have tried the following:
1. impedance matching with a shunt inductor of 1.5nH on both RF and LO inputs. This improved linearity but not the gain.
2. To bias the bottom two switch trasistors so that they operate in the saturation region (Vgs< Vds, right?) but that makes the gain even worse. I tried to bias them by means of introducing an offset source at the gate of the transistors.
3. Make the transistors wider. This does help a bit but even with 300 um gates my gain is still negative.
I would very much appreciate any advice anybody can give me.
I am a first time analogue designer and need help with my Gilbert cell mixer for Bluetooth (CMOS 0.18um technology). The problem is that my circuit has a negative gain though, I believe, 10 dB is achievable. I have tried the following:
1. impedance matching with a shunt inductor of 1.5nH on both RF and LO inputs. This improved linearity but not the gain.
2. To bias the bottom two switch trasistors so that they operate in the saturation region (Vgs< Vds, right?) but that makes the gain even worse. I tried to bias them by means of introducing an offset source at the gate of the transistors.
3. Make the transistors wider. This does help a bit but even with 300 um gates my gain is still negative.
I would very much appreciate any advice anybody can give me.