Anglia Live

In today’s multichannel, wideband multioctave tuning RF receivers, it is often necessary to eliminate unwanted blockers to preserve the fidelity of signals of interest. Filters play an essential role in reducing these unwanted
signals, particularly in the receiver RF front end and local oscillator (LO) portions of these systems. The ADMV8818-EP provides a compact and effective solution for isolating the signal of interest.

The ADMV8818-EP from Analog Devices is a fully monolithic microwave integrated circuit (MMIC) that features a digitally selectable frequency of operation. The device features four independently controlled high-pass filters (HPFs) and four independently controlled low-pass filters (LPFs) that span the 2 GHz to 18 GHz frequency range.

The flexible architecture of the ADMV8818-EP allows the 3 dB cut-off frequency (f3dB) of the high-pass and low-pass filters to be controlled independently to generate up to 4 GHz of bandwidth. The digital logic control on each filter is 4 bits wide (16 states) and controls the on-chip reactive elements to adjust the f3dB. The typical insertion loss is 9 dB, and the wideband rejection is 35 dB, which is ideally suited for minimizing system harmonics.

Functional Block Diagram

The ADMV8818-EP consists of two sections, the input and the output section. The input section has four high-pass filters and an optional bypass configuration that is selectable by the two SP5T RFIN switches. Similarly, the output section has four low-pass filters and an optional bypass configuration that is selectable by the two SP5T RFOUT switches. Because the input and output sections are independent from one another, the chip can be configured for any combination of high-pass filter, low-pass filter, or bypass configuration. The two SP5T RFIN switches are controlled simultaneously with a 3-bit digital control. Likewise, the two SP5T RFOUT switches are controlled simultaneously with a 3-bit digital control. This control scheme creates a total of 25 possible combinations of switch settings, achieving many possible filter responses.

The ADMV8818-EP tuneable filter can be used as a smaller more cost-effective alternative to large switched filter banks and cavity tuned filters, and this device provides a dynamically adjustable solution in advanced communications applications. The device is housed in a compact 9mm x 9mm, 56 terminal LGA package and features a wide operating temperature range of -55°C to +105°C

The ADMV8818-EP tuneable high-pass & low-pass filter is suitable for a range of applications including Test and Measurement Equipment, Radar, Communications Equipment, Industrial and Medical equipment.

Evaluation Board

The ADMV8818-EP tuneable high-pass & low-pass filter is supported by the ADMV8818-EVALZ evaluation board which incorporates the ADMV8818 chip, as well as a negative voltage generator, low dropout (LDO) regulators, and an interface to the EVAL-SDP-CS1Z (SDP-S) system demonstration platform (SDP) to allow fast, simple and efficient evaluation. The negative voltage generator and LDO regulators allow the ADMV8818 to be powered by either the 5 V USB supply voltage from the PC via the SDP-S or by using two external power supplies.

The ADMV8818-EP can be programmed using a 4-wire serial port interface (SPI) whilst the SDP-S controller allows the user to interface with the ADMV8818 SPI through the Analog Devices Analysis | Control | Evaluation (ACE) software. The ADMV8818-EP has two modes of operation: SPI write and SPI fast latch. SPI write mode is the normal operating mode, whereas SPI fast latch mode is used to sequence through the on-chip lookup table (LUT) using the internal state machine.