# A Ku-Band GaAs Multifunction Transmitter and Receiver Chipset
## 4 Multifunction Transmitter and Receiver  
The transmitter and receiver are designed by integrating the circuit blocks described in Section 3. The chip micrographs are shown in Figure 17. Each chip occupies \(4.2\times 2.8\) mm\({}^{2}\), including probing pads. On-wafer probing measurement is performed with a vector network analyzer, noise figure analyzer and power meter. The input digital signals of SPC (D\({}_{\text{in}}\), CLK, EN) are generated by NI USB-6361 X series multifunction DAQ. To facilitate the measurement for 512 states, the measurement equipment and DAQ are controlled by LABVIEW. The measured gain, matching and output power of the multifunction transmitter chip are shown in Figure 18. The gain exhibits a peak value of 16.5 dB at 14.7 GHz and more than 10 dB over the Ku-band. The input and output matching are below \(-\)10 dB over the Ku-band. The OP1 dB and P\({}_{\text{sat}}\) at 15 GHz are 19.2 and 19.8 dBm, respectively. Figure 16: Measurement results of the LNA. (**a**) Gain and noise figure, (**b**) input and output matching. Figure 17: Chip micrographs of (**a**) the multifunction transmitter, (**b**) receiver. The measured gains for 32 attenuation states of the multifunction transmitter are depicted in Figure 19a. The gain varies from 1.5 to 16.5 dB at 14.7 GHz. The attenuation range is 13.9 to 15.9 dB over the Ku-band. The RMS attenuation and parasitic phase errors over 32 attenuation states are shown in Figure 19b. The averaged RMS attenuation and parasitic phase error values over the Ku-band are 0.6 dB and 2.9\({}^{\circ}\), respectively. The measured phase shifts of the multifunction transmitter for 16 phase states are shown in Figure 20a, confirming a full 360\({}^{\circ}\) shift. The RMS phase and parasitic amplitude errors over 16 phase states, shown in Figure 20b, are 6.4\({}^{\circ}\) and 0.8 dB, respectively, on average, over the Ku-band. The measured gain, matching and noise figures of the multifunction receiver chip are shown in Figure 21. The multifunction receiver exhibits a peak gain of 17.3 dB and noise figure of 2.5 dB at 15 GHz. The noise figure over the Ku-band is below 4.3 dB. The measured input and output matching are below \(-7\) and \(-13.2\) dB, respectively, over the Ku-band. Figure 19: Attenuation performance of the multifunction transmitter: (**a**) gain in the 32 attenuation states, (**b**) RMS attenuation and parasitic phase errors. Figure 18: Measurement results of the multifunction transmitter in the reference state: (**a**) gain and matching performance, (**b**) output power and power gain versus input power at 15 GHz. The measured gains for the 32 attenuation states of the multifunction receiver are depicted in Figure 22a. The gain varies from 2.5 to 17.3 dB at 15 GHz. The attenuation range is 13.8 to 16 dB over the Ku-band. The RMS attenuation and parasitic phase errors over the 32 attenuation states are shown in Figure 22b. The averaged RMS attenuation and parasitic phase error values over the Ku-band are 0.7 dB and 2.2\({}^{\circ}\), respectively. Figure 21: Measured gain, noise figure and matching performance of the multifunction receiver. Figure 20: Phase shift performance of the multifunction transmitter: (**a**) phase shift in the 16 phase states, (**b**) RMS phase and parasitic amplitude errors. The measured phase shifts of the multifunction receiver for the 16 phase states are shown in Figure 23a, confirming a full 360\({}^{\circ}\) shift. The RMS phase and parasitic amplitude errors over the 16 phase states, shown in Figure 23b, are 5.1\({}^{\circ}\) and 0.8 dB, respectively, on average, over the Ku-band. In Table 3, the performance of the multifunction transmitter and receiver in this work is summarized and compared with previously reported GaAs multifunction chips. The multifunction transmitter and receiver achieve a high level of integration, including the 5-bit digital attenuator, 4-bit digital phase shifter, 9-bit SPC and amplifier, thus presenting high gain and wideband performance.