AWR Success Stories

VTT and Cadence 2 www.cadence.com/go/awr In addition, FDM allows accurate phase measurements supporting medical applications such as remote monitoring of heartbeat and breathing rates from the detection of small movements of the chest. Requirements for the radar system included fast imaging >200Hz, range resolution <5cm, multitarget acquisition, moving target capability, and high sensitivity to micromotion, all in a small, lightweight, low-cost footprint. The key challenge for the design was system feasibility, which were studied using AWR VSS software. The actual chip design was made possible through simulation with AWR Microwave Office software using the IHP foundry silicon germanium (SiGe) process design kit (PDK) and EM verification of the on-chip passive components. The specifications for the system were: f 1.5° angle resolution with 8TX - 8RX MIMO f 3-5cm range resolution f 160° horizontal field of vision (FoV) f 25° elevation FoV (3D systems with 160° x 160° FoV are also available) Solution VTT designers used AWR Design Environment software for this project. A simple diagram of the system implemented in AWR VSS software is illustrated in Figure 2. The signal source is divided between the transmit and receive sides and details of the transmitter power amplifier (PA) and receiver low-noise amplifier (LNA) chains (not shown) can be further developed with results from AWR Microwave Office software co-simulations. The transmitter and receiver signal paths must be well-isolated to operate properly, which impacts certain design aspects and limits the acceptable transmit power level. Otherwise, power from the transmit side will leak into the receiver circuit, poten- tially saturating the LNA and/or down-conversion mixer. Figure 2: Basic construction of FMCW radar systems in AWR VSS software, amplifier stages (PA, LNA), and individual MIMO channels (not shown) Figure 2 illustrates the signal being radiated between the transmit and receive antennas through a AWR VSS software radar target model that includes properties such as the radar cross section, distance, velocity, and ambient condi- tions. The mixer will down-convert the signal that was reflected from the target, using the swept frequency from the voltage-controlled oscillator (VCO) as the local oscil- lator. Taking the difference of these two signals creates a beat signal that is directly proportional to the distance to the target. This IF is fed to an analog-to-digital (A/D) converter for signal processing. This signal processing extracts the target distance using a fast Fourier transform (FFT) algorithm. By using multiple antennas, the Fourier transform also supports digital beamforming in order to produce a 2D image of the detected object. AWR VSS software was used to study the main aspects of the MIMO radar at the system level. The software provides a block-level representation of the signal sources, LNAs, mixers, PAs, frequency multipliers, antennas, and radar targets (Figure 3) enabling the designers to tune and optimize all the key parameters and incorporate real-world operation of the radar system as more circuit-level detail was added. Figure 3: AWR VSS software's system diagram of the FMCW MIMO radar The core of the radar system is the TX and RX RF integrated circuits (RFICs), both of which support four channels occupying a very small area. Additional chips can be added to the system to increase the number of channels. It is advantageous for one RFIC to support multiple channels to reduce the assembly effort and to allow scaling for a system with a very large number of channels. Separate TX and RX chips enable independent TX/RX scaling, lower the TX/RX leakage, and support closer placement to the feed structure to reduce PCB losses. AWR Microwave Office software was used in combination with the AWR AXIEM EM analysis to design the TX and RX chips from the transistor level using the IHP SG13S SiGe PDK available for AWR software. The detailed schematic of the PA was developed using components from the foundry PDK for AWR Microwave Office software. IN OUT LO 1 2 1 2 CHIRP GENERATOR fc -f +f 1 TARGET MODEL 1 2 3 4 TX Antenna RX Antenna Signal Generation Radar Target Model CHIRP GENERATOR fc -f +f 1 1 2 3 1 2 3 1 2 3 1 2 3 1 2 3 1 2 3 CE R 1 2 3 CE R 1 2 3 1 2 3 1 2 3 4 1 2 1 2 3 4 Chirp Generation 57 - 60 GHz Sweep Modulator Modulator Antennas and Radar Target Model Demodulator Demodulator RX 2: IF Signal to Digital Backend RX 1: IF Signal to Digital Backend Offset Frequencies 1MHz and 2 MHz

• Cover