Tunable Bandpass Filter ( 30-512 MHz )

Application:

• Applications where small size, low power, and high performance are needed

• Military Radios

• Military Radar

• SATCOM

• Test and Measurement Equipment

• Industrial and Medical Equipment

Feature:

• 4 dB typical insertion loss for a 5% filter

• 21 dBc typical selectivity at fc   ± 10%

• 0 dBm RF operating power

• 18 µs typical tune time (Serial Tuning)

• 9 µs typical tune time (Parallel Tuning)

• Low DC power consumption

Description:

Internal Switch 3-band, low cost, miniature, high-performance tunable filter. designed to have the best insertion loss and Q in the smallest package possible. The size is 47 mm x 42 mm x 7. 1 mm

Control Mode:

This product offers two control methods: 3-wire SPI control and 8-bit parallel control.

When the SER/PAR pin is set to high level and the CS pin is connected to the STB pin, the device enters SPI mode. When the SER/PAR pin is grounded, the device enters 8-bit parallel control mode.

 Operation Principle :

SPI Command: The customer's MCU sends 2 bytes of data (0–250) to the module via SPI. The data length is 16 bits. Bits 15–10 are invalid, bits 9–8 are segment selection, and bits 7–0 are the data value. Upon receiving the data, the module looks up the corresponding table and prepares new parameters.

Output Trigger: The customer's MCU sends a low-level pulse to the OUT_TRIG pin. The module immediately applies the new parameters and establishes a new operating state.

Address Code Calculation:
Address code = {(fx – flow) / (fhigh – flow)} × 250

Where:

fx = desired tuning center frequency within the band

flow = lowest frequency in the segment

fhigh = highest frequency in the segment

250 = total number of steps within the segment

If the result contains a decimal, it shall be rounded to the nearest integer

Example:
Center frequency fx = 450 MHz
Address code = {(450 – 225) / (678 – 225)} × 250 = 124
Binary code: 0111 1100

Parallel control :

The Parallel tune command interface is an 8-bit wide synchronous parallel interface with a two-byte load. There are always 16 data bits per parallel tune regardless of the tune mode used. Any bits that do not affect the frequency offset of the filter should always be set to 0. A7 is the most significant bit and A0 is the least significant bit. Keeping SER/PAR pulled to GND during power up will enable the parallel tune command interface.

Functional Description :

Tune Commands

The tune command is a two-byte load tune word. The first byte (MSB) is the band the filter should tune to. The

Second, byte (LSB) is the frequency offset in the chosen band. The tune command is formatted the same for both SPI and parallel interface modes.

‍ ‍

Tune Time :

‍Tune times include internal processing of the tune command data and the 90% settled RF amplitude response time of the filter. This time excludes the time required to load the tune command into the filter. Low-level signal measurements were utilized to show the receive tune time that can be expected.

‍In addition, RF power in excess of -10 dBm is considered to be “hot switching” of the filter. The data taken in was taken with 0 dBm input but this does not imply that tuning operation of the filter with that level can be done reliably. It is recommended that RF power remains less than -10 dBm during a tune event.

1.       No routing is allowed on the bottom side of the PCB. Do not connect to ground or any voltage level. DC blocking capacitors are required on both input and output. The yellow area is the exposed copper (solderable) area.

2.       It is not recommended to use a hot air gun for soldering the sample.

Note: Top Side looking down