Temperature-Insensitive Ka-Band Transceiver With Ultralow-Noise Self-Calibrated Low Dropout Regulator in 65-nm CMOS

This article proposes a Ka-band transceiver with an integrated local oscillator (LO) generator and multiple low dropout regulators (LDOs) to eliminate the strict requirements to the external power supply network. The proposed self-calibrated LDO eliminates the use of a bandgap reference circuit and its large flicker noise contribution in traditional power regulators to achieve ultralow-noise performance. The output of the proposed LDO is self-calibrated with temperature and process variations by autoconfiguring the feedback coefficient through a digital loop to guarantee the stable performance of its loaded high-speed circuits. The stable gain and output power of the transceiver with temperature variation are achieved by on-chip multiple self-compensation schemes, which include a self-sensing LDO for the power amplifier, a constant- $G_{\!m}$ bias circuit for the amplification stages, and the temperature-compensated intermediate-frequency amplifiers (TC IFAs) with proportional-to-absolute-temperature (PTAT) gain to further compensate for the gain deviation caused by the second-order effect and large-signal performance difference. Implemented in 65-nm CMOS technology, measurements indicate that the output noise of the proposed LDO is as low as 15 nV/sqrt (Hz) at 10-kHz offset and the integrated power network greatly reduces the noise influence on the LO signal compared with the traditional bandgap-referenced LDO. Furthermore, due to the adoption of the proposed temperature compensation scheme, the small-signal gains of the receiver and transmitter only fluctuate by 1.1 and 1.3 dB from $- 40\,\,^{\circ }\text{C}$ to $85~^{\circ }\text{C}$ , respectively, and the output saturated power of the transmitter varies by 0.7 dBm over the entire temperature range.