ADMV4821

The ADMV4821 is a silicon germanium (SiGe), 24 GHz millimeterwave (mmW) to 29.5 GHz mmW 5G beamformer. The RF IC is highly integrated and contains 16 independent channels with both transmit and receive functionality. The ADMV4821 supports eight horizontal and eight vertical polarized antennas via the independent RFV and RFH inputs/outputs common pins.

In transmit mode, both the RFV and RFH input signals are split via two independent 1:8 power splitters and pass through the eight, independent, corresponding transmit channels. In this mode, each channel includes a vector modulator (VM) to control the phase and two digital variable gain amplifiers (DVGAs) to control the amplitude.

In receive mode, input signals pass through two sets of eight receive channels (either vertical or horizontal) and are combined via one independent 8:1 combiner connected to the RFV pin and one independent 8:1 combiner connected to the RFH pin. In this mode, each channel includes a VM to control the phase and a DVGA to control the amplitude.

The VM provides a full 360° phase adjustment range in either transmit or receive mode. The VM provides six bits of resolution for 5.625° phase steps.

In transmit mode, the total DVGA dynamic range adjustment range is 32.4 dB. The DVGAs provide five bits or six bits of resolution, resulting in 1.0 dB or 0.5 dB amplitude steps, respectively.

In receive mode, the DVGA allows for 17.1 dB of dynamic range adjustment. The DVGA also provides six bits of resolution, resulting in 0.5 dB amplitude steps. The DVGAs provide a flat phase response across the full gain range.

The transmitter channels contain individual power detectors to detect and calibrate the gain for each channel as well as the channel to channel gain mismatch. Directly connect the ADMV4821 RF ports to a patch antenna to create a dual polarization mmW 5G subarray.

Users can program the ADMV4821 by using a 3-wire or 4-wire serial port interface (SPI). The integrated on-chip low dropout (LDO) regulator generates the 1.8 V supply for the SPI circuitry to reduce the number of supply domains required. There are various SPI modes to enable fast startup and control during normal operation.

Users can either set the amplitude and phase for each channel individually or program multiple channels simultaneously by using the on-chip memory for beamforming. The on-chip memory can store up to 256 beam positions, which can be allocated for either transmitter or receiver mode in any combination. In addition, four address pins allow SPI control of up to 16 devices on the same serial lines. Dedicated horizontal and vertical polarization load pins also synchronize all devices in the same array. There is a horizontal and vertical polarization transmit and receive mode control pins (TRXV and TRXH) for fast switching between transmit and receive mode.

The ADMV4821 comes in a compact, thermally enhanced 10 mm × 10 mm, RoHs compliant land grid array (LGA) package. The ADMV4821 operates over the −40°C to +95°C case temperature range. This LGA package allows users to heat-sink the ADMV4821 from the top side of the package for the most efficient thermal heatsinking and to allow flexible antenna placement on the opposite side of the printed circuit board (PCB).

Throughout the figures in the data sheet, Tx means transmit (or transmitter) and Rx means receive (or receiver).

APPLICATIONS