10 MHz to 20 GHz Integrated Vector Network Analyzer Front End

The ADL5960 is a wideband, small form factor vector network analyzer front end consisting of a resistive bidirectional bridge, downconversion mixers, programmable IF amplifiers and filters, and a highly flexible local oscillator (LO) interface. The bridge provides >14 dB of directivity up to 17 GHz. The primary transmission line from RFIN to RFOUT is wideband matched to 50 Ω with only 1.1 dB loss at low frequencies, increasing to 1.8 dB loss at 20 GHz.

The ADL5960 supports several different LO interface configurations that simplify the clocking design of a vector network analyzer (VNA) solution as well as the interfacing of the device to an analog-to-digital converter (ADC). The frequency divider and multipliers in the LO interface enable measurement sweeps beyond the operating frequency range of the LO source, enabling operation over the full 20 GHz frequency range of the ADL5960 using a 6 GHz synthesizer. The IF frequency offset mixer, driven through the offset interface formed by the OFP and OFM pins, enables further simplification by allowing the swept RF and LO interfaces to share the same frequency source. The frequency of the IF output signals is then determined by the low-frequency source driving the OFP/OFM interface. When this interface is driven at the ADC sample frequency with the divide by 4 enabled, it automatically centers the IF output signal in the first Nyquist zone.

The IF filters with programmable bandwidth and IF amplifiers with individually programmable gain enable simultaneous dynamic range optimization of the IF output signals of the forward channel (IFFP, IFFM) and reverse channel (IFRP, IFRM). The IF amplifiers have an adjustable output common-mode level, sufficient drive capability, and wide output voltage swing to enable direct interfacing to a wide range of ADCs.

All configurations and functions in the ADL5960 are fully programmable through a 3-wire serial peripheral interface (SPI). The ADL5960 is offered in a 3 mm × 4 mm body and 0.68 mm package height, 26-lead land grid array (LGA).

APPLICATIONS

* Broadband, multiport vector network analyzers

* S parameter magnitude and phase measurement

* Inline RF power measurement

* Automated test equipment

* Reflectometers

* Materials analysis

* Wideband integrated bidirectional bridge

* Raw directivity: 24.1 dB at 1 GHz, 12.8 dB at 18 GHz

* Low insertion loss: 1.1 dB at 1 GHz, 1.9 dB at 18 GHz

* Return loss: >12 dB typical

* SPI configurable LO interface

* Divide by 2; multiply by 1, 2, or 4

* Offset LO interface enables drive with fRF = fLO

* Single-ended or differential drive

* SYNC function—synchronization across multiple devices