# 25-34 GHz Single-Pole, Double-Throw CMOS Switches for a Ka-Band Phased-Array Transceiver
## 3 Implementation and Measured Results  
The proposed SPDT CMOS switches were fabricated using a 1P8M 65-nm CMOS process. Figure 12a,b show microphotographs of the proposed Ka-band CB and DSB SPDT switches, which have identical pads and inductors--\(L_{DS}\), \(L_{ANT}\), and \(L_{TRX}\)--and differ only in the core area. The total size of the chip, including all the pads, is 460 \(\upmu\)m \(\times\) 520 \(\upmu\)m, and the area of the switch is 260 \(\upmu\)m \(\times\) 230 \(\upmu\)m. All control pads, except the RF ports, were protected against electrostatic discharge (ESD). The test chips were glued to a printed circuit board and RF signals were connected directly to the measuring equipment using a ground-signal-ground (GSG) with a nominal impedance of 50 \(\Omega\). A supply voltage of 1 V was used for switch control. Small-signal measurements were recorded using a Keysight PNA E8363C network analyzer (Keysight, Santa Rosa, CA, U.S.). The linearity performances were measured by a Keysight N9030A spectrum analyzer (Keysight, Santa Rosa, CA, U.S.) and two E8257D signal sources (Keysight, Santa Rosa, CA, U.S.) with a power combiner.  
Figure 13 shows the simulated and measured insertion losses and isolation performances of the CB and DSB switches. The loss from the GSG pads and interconnection line between the pads and the core switch, which was compensated, was about 0.3 dB. The measured insertion losses of the CB switch was less than 2.3 dB between 25 GHz and 34 GHz. The minimum insertion loss was 2.1 dB at 28 GHz. The results from the measurements and simulations were in good agreement, with a difference of less than 0.6 dB. The maximum isolation measured was \(-\)32 dB, and achieved at 27 GHz, as intended. As shown in Figure 13a, the measured isolation was greater than 19 dB, between 25 GHz and 34 GHz. With the DSB switch, between 25 GHz and 34 GHz, the measured insertion loss was less than 2.5 dB, which was slightly higher than with the CB switch, because the magnitude of the internally generated negative supply voltage, \(V_{NN}\), was smaller than \(V_{DD}\). The minimum insertion loss was 1.93 dB at 24.4 GHz. The results from the measurements and simulations were in good agreement,  
Figure 11: (**a**) Simulated insertion loss of a DSB switch, and (**b**) insertion loss contribution at 28 GHz.  
Figure 12: Microphotographs of (**a**) the CB SPDT switch and (**b**) DSB SPDT switch.  
with a difference of less than 0.6 dB. As shown in Figure 13b, the measured isolation was greater than 16 dB, between 25 GHz and 34 GHz. The minimum isolation measured was \(-\)34.81 dB, occurring at 30 GHz. Figure 14a,b shows that both the CB and DSB switches had very low return losses, which were less than 17 dB in the operating bandwidth.  
Figure 15a,b shows the output powers of the fundamental tones and third order intermodulation tones of the CB and DSB switches, respectively, according to the two-tone input power. Due to the lack of a high power mm-wave signal source, the input power was limited to 10 dBm. The third order input intercept (IIP3) points were calculated using two-tone signals at the frequency of 28 GHz. Each tone power was 7 dBm and the tone spacing was 100 MHz. The measured IIP3s of the CB and DSB switches were 38.4 dBm and 39 dBm, respectively.  
Figure 14: Return losses of (**a**) the CB SPDT switch and (**b**) DSB SPDT switch.  
Figure 15: Linearity performances of (**a**) the CB SPDT switch and (**b**) DSB SPDT switch with respect to the input power at 28 GHz.