A 16-element fully integrated 28-GHz digital beamformer combines with a custom eight-layer LTCC substrate with a 4 $\times \,\,{4}$ patch antenna array for a complete 16-element single-chip 28-GHz millimeter-wave (mm-wave)-to-digital beamforming system. Sixteen-element digital beamforming in a single integrated circuit (IC) represents an excellent tradeoff between die size, signal loss, and I/O routing complexity. Per-element RX slices with an inductor-less mm-wave front end and 4 $\times $ parallel continuous-time bandpass delta–sigma analog-to-digital conversion (ADC) arrays enable compact mm-wave-to-digital conversion. The 4 $\times $ parallel ADC array provides in-built finite-impulse response (FIR) filtering for additional harmonic suppression and anti-alias filtering. ADC sampling of a high (1 GHz) IF facilitates single-phase mm-wave local oscillator (LO) routing and moves the I/Q mixing into the digital domain. Optimum bump and RX slice placement shortens LO and mm-wave signal routing and reduces signal loss. Bit-stream processing (BSP) takes advantage of the narrow bit-width raw outputs of the RX slices to implement digital beamforming with area- and energy-efficient MUXes. The prototype 16-element beamformer generates four independent, simultaneous beams. Over-the-air measurements confirm accurate 3-D beam patterns and indicate a measured overall noise figure of 7 dB and QAM-4 error vector magnitude (EVM) of −18 dB.

中文翻译：

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16元素完全集成的28 GHz数字RX波束成形接收器

16元素完全集成的28 GHz数字波束形成器与定制的8层LTCC基板和4 $ \ times \，\，{4} $ 贴片天线阵列，用于完整的16元素单芯片28 GHz毫米波（mm-wave）到数字波束成形系统。单个集成电路（IC）中的16元素数字波束成形代表了芯片尺寸，信号损耗和I / O路由复杂度之间的极佳折衷。具有无电感器毫米波前端和4个元素的每元素RX切片 $ \次$ 并行连续时间带通delta-sigma模数转换（ADC）阵列可实现紧凑的毫米波数模转换。4 $ \次$ 并行ADC阵列提供内置的有限脉冲响应（FIR）滤波，以实现额外的谐波抑制和抗混叠滤波。高（1 GHz）中频的ADC采样有助于单相毫米波本地振荡器（LO）布线，并将I / Q混频移至数字域。最佳的凸块和RX切片位置可缩短LO和毫米波信号的路由，并减少信号损耗。比特流处理（BSP）利用RX slice的窄比特宽度原始输出来实现具有面积和能源效率高的MUX的数字波束成形。原型16元素波束形成器生成四个独立的同时波束。空中测量可确认准确的3-D波束方向图，并表示测得的总噪声系数为7 dB，QAM-4误差矢量幅度（EVM）为-18 dB。