wirelessZONE Products for the week of June 13, 2011

Peregrine Semiconductor Says…

PE64904/5: 5-bit Digitally-Tunable Capacitors
Variable capacitors enable frequency-agile Tunable Networks

Peregrine Semiconductor Corporation, a fabless provider of high performance radio-frequency (RF) integrated circuits (ICs), announced availability of the RoHS compliant PE64904 and PE64905 DuNE Digitally Tunable Capacitors (DTCs). The new 5-bit, 32-state digitally controlled variable capacitors provide a monolithically integrated impedance tuning solution for demanding RF applications. These UltraCMOS-based devices enable wide-band tunable networks, minimizing mismatch losses, improving system efficiency and reducing radio complexity for a cost-effective tuning solution. Design applications for the new DTC devices range from tunable filters and matching networks to RFID, antenna tuning and other wireless communications where tunability and optimal system performance is critical.

“The need for a monolithically integrated, easy-to-use impedance tuning device has never been greater, and we are pleased to commercially release these new devices,” said Mark Schrepferman, marketing director for Peregrine’s HPS business unit. “Our initial DuNE technology launch enabled prototype DTCs for cellular handset and mobile TV applications. In identifying the performance requirements of the broader market, Peregrine engineers designed the latest DTCs to address a wide variety of complex tunable architectures,” he added.

EN-Genius Says…

Getting a digitally-tuned capacitor for RF isn’t limited to just getting the right steps of capacitance themselves. To be of use in real world conditions the capacitor must be capable of handling a decent amount of power so that is can be inserted as close to the element being tuned (probably the antenna, in many cases) as possible. Peregrine have done that with the PE64904 and PE64905 offering performance from 100 MHz to 3 GHz.

The difference between the two parts is the control interface. The PE64904 uses a 3-wire SPI compatible serial interface while the PE64905 uses a 2-wire I2C serial interface.

Each device contains a system of five capacitors (5 bit) that can be switched into circuit in either a series or shunt configuration. In series there is a 6.6 to 1 tuning ratio offered with the 32 steps of capacitance of about 126 fF each changing the absolute value from about 0.7 pF to 4.6 pF (at 100 MHz). In the shunt configuration the tuning ratio is about 4.6 to 1 with 32 steps of about 131 fF with an absolute value range from about 1.12 pF to 5.18 pF (also at 100 MHz). Equivalent series resistance is lower than 1.5 Ω. The Q factor is better than 25 across the board while harmonics are lower than -36 dBm for both second and third across the operating spectrum.

At the same time the devices can handle power inputs up to +38 dBm (about 7 W into 50 Ω) with 30 Vpeak while the power supply range can be that typically now used for portable RF amplifiers from about 2.3 V to 3.6 V. Quiescent is a typical 140 µA. 2 kV human body model ESD protection is provided on both the RF input and output pins as well as on the serial interface pins. The nominal control voltages are at 1.8 V

Like all of Peregrine’s silicon-on-sapphire UltraCMOS products the parts are immune to latch-up; switching times are less than 12 µs with 10 µs settling time. VSWRs were not available in the information to hand.

These parts will find ready acceptance in antenna tuning in portable RF products as well as a tuning elements in filter networks and diversity/curtain phase shifters.

The PE64904 and PE64905 are both sampling in QFN-10 with production slated for Q3 of 2011. Pricing will be at $1.45 in 10-k piece lots. Evaluation kits are available.

Data Sheet (requires registration)