14.7 An Adaptive Analog Temperature-Healing Low-Power 17.7-to-19.2GHz RX Front-End with ±0.005dB/°C Gain Variation, <1.6dB NF Variation, and <2.2dB IP1dB Variation across -15 to 85°C for Phased-Array Receiver

Phased arrays have demonstrated great potential in 5/6G communication, radar and sensor applications [1 -4]. To achieve excellent performance, phased arrays require lownoise and high-linearity front-ends [5]. Most importantly, arrays demand uniform performance from all elements for optimum receiving G/T value and transmission effective isotropic radiated power (EIRP) [6]. Figure 14.7.1 exemplifies it with an array whose antenna element has 3dBi uniform gain on one side and no radiation on the other side. When all elements in an 8×1 linear array with a λ/2 space have identical characteristics, the array presents a 19dBi gain in the normal direction. Any temperature change in the array can be decomposed into an absolute temperature change superposed with a relative temperature variation. When the absolute temperature increases, the frontend gain decreases by as much as -0.1dB/°C [1]. When there is non-uniform solar radiation or heat generation inside the array, the relative temperature variation may present a gradient or a parabolic distribution. Taking a 64×1 array as an example, when there is a gain/phase mismatch with an average value of 0.125dB/1.25° between adjacent elements in a parabolic distribution locating at the center of the array, the formed beam presents a 1.4dBi main-lobe reduction in the normal direction and an 11.9dBi side-lobe degradation, shown in Fig. 14.7.1. It also shows an active array receiver front-end highlighting all the temperature-sensitive blocks. Calibration can adjust temperature-dependent performances [7]. However, periodic calibration inevitably takes time overhead and prevents array systems from full-time operations. Digital background calibration allows systems to operate uninterrupted, but may induce antenna boresight instability due to abrupt gain/phase change. In contrast, analog background calibration like adaptive healing design can resolve the above issues [8]. In this paper, we present an adaptive analog temperature healing receiver front-end with ±0.005dB/°C gain variation from -15 to 85°C environment temperature for a 17.7-to-19.2GHz phased array.

Phased arrays have demonstrated great potential in 5/6G communication, radar and sensor applications [1– 4]. To achieve excellent performance, phased arrays require low-noise and high-linearity front-ends [5]. Most importantly, arrays demand uniform performance from all elements for optimum receiving G/T value and transmission effective isotropic radiated power (EIRP) [6]. Figure 14.7.1 exemplifies it with an array whose antenna element has 3dBi uniform gain on one side and no radiation on the other side. When all elements in an linear array with a space have identical characteristics, the array presents a 19dBi gain in the normal direction. Any temperature change in the array can be decomposed into an absolute temperature change superposed with a relative temperature variation. When the absolute temperature increases, the frontend gain decreases by as much as [1]. When there is non-uniform solar radiation or heat generation inside the array, the relative temperature variation may present a gradient or a parabolic distribution. Taking a array as an example, when there is a gain/phase mismatch with an average value of between adjacent elements in a parabolic distribution locating at the center of the array, the formed beam presents a 1.4dBi main-lobe reduction in the normal direction and an 11.9dBi side-lobe degradation, shown in Fig. 14.7.1. It also shows an active array receiver front-end highlighting all the temperature-sensitive blocks. Calibration can adjust temperature-dependent performances [7]. However, periodic calibration inevitably takes time overhead and prevents array systems from full-time operations. Digital background calibration allows systems to operate uninterrupted, but may induce antenna boresight instability due to abrupt gain/phase change. In contrast, analog background calibration like adaptive healing design can resolve the above issues [8]. In this paper, we present an adaptive analog temperature healing receiver front-end with ± gain variation from -15 to environment temperature for a 17.7-to-19.2GHz phased array.