The goal of this project is to design an analog baseband section suitable for 60 GHz receivers. The baseband section is required to select the desired channel and amplify the signal to a level that is near the full scale voltage swing of the ADC. The chain consists of a transimpedance amplifier, an active filter and a programmable gain amplifier. The overall chain's order is six. The LPF is of fourth order and both of the TIA and PGA are of the first order.
- Transimpendace amplifier : combines the signal and converts the input current coming from the beamfoarmer repeaters into voltage, so it requires low input impedance to sense the current. It contributes one pole to the overall system's transfer function and provides gain programmabiility.
- Low-pass filter : The LPF is of fourth order, and it's build using a cascade of two biquadratic cells, it's function is to select the desired channel while providing the required attenuation to the folding band of the interfereing channel.
- Programmable gain amplifier : It is the last stage of the chain. It provides gain programmability and a pole to the overall system's transfer function.
| Selectivity | 6th order LPF |
| Real poles frequency | 700 MHz |
| Complex poles Q-factor | 1.45 |
| Cut-off frequency | 960 MHz |
| Cutt-off accuracy | 10 % |
| In-band amplitude ripple | 1.5 dB |
| Group delay | < 4.5 ns |
| Gain range | 0-20 dB |
| Gain step | 1 dB |
| PAPR | 7.8 dB |
| SDR | 25 dB |
| IIP3 (0dB gain) | 4.8 dBm |
| Input-Referred-Noise (20 dB gain) | -142 dBm/Hz |
- For the TIA, a two stage miller compensated opamp topology have been used.
-The Cc performs pole splitting and the Rc is used to deal with the problem of the zero.
- The CMFB network is used to make the output common mode level well defined.
- A fourth order LPF is bulit using a cascade of two biquad cells with a source follower-based biquad topology.
- The used series shunt feedback yields to a high capacitive input impedance.
- The series shunt structure reduces the output impedance due to the feedback. So, the PGA can drive the ADC without affecting it's frequency and linearity performance.
- The CMFB network is used to make the output common mode level well defined.
[1] S. D'Amico, A. Spagnolo, A. Donno, V. Chironi, P. Wambacq and A. Baschirotto, "A Low-Power Analog Baseband Section for 60-GHz Receivers in 90-nm CMOS," in IEEE Transactions on Microwave Theory and Techniques, vol. 62, no. 8, pp. 1724-1735, Aug. 2014, doi: 10.1109/TMTT.2014.2332877.
[2] S. D'Amico, A. Spagnolo, A. Donno, P. Wambacq and A. Baschirotto, "A 9.5mW analog baseband RX section for 60GHz communications in 90nm CMOS," 2011 IEEE Radio Frequency Integrated Circuits Symposium, 2011, pp. 1-4, doi: 10.1109/RFIC.2011.5940689.
The goal of this project is to design an analog baseband section suitable for 60 GHz receivers.