When designers are working on frequency conversion, they need to decide between an active mixer (typically with wider bandwidth, however suffering from higher noise and lower linearity) and a passive mixer (lower noise, higher linearity though tends to be narrowband). For high performance applications, the solution has been to combine a number of passive mixers to achieve broadband coverage. The team at Analog Devices (ADI) decided to interpret this as a challenge, and set out to design a broader bandwidth passive mixer.
The result is the ADL5811 and ADL5812 wideband passive mixers, released today and previewed at the IMS2011 show in Baltimore next month. Recently, I spoke with Mike Chowkwanyun, Product Manager, RF Group, Analog Devices, Inc., about the new products. He explained that with this type of wideband mixer, "you can reduce BOM for the mixer, and eliminate each band's specific matching elements. Now designers can use just one device that they can program through the RF balun."
The new devices feature a serial port interface with a bias adjust feature (when there are different RF signal levels, you can optimize between operating conditions that give the best noise figure or linearity performance) as well as individual channel power-down control.
Wideband, Limiting LO Amplifier
Programmable RF Balun Transformer
- 250 MHz to 2760 MHz
- Generates high voltage square wave with fast rise time; no DC current penalty over narrowband passive mixers
Programmable low-pass filter (attached to output of the mixer stage)
- 700 MHz to 2800 MHz
- Provides a balanced RF input signal drive to the mixer core
- Reduces early compression of the IF amplifier due to unwanted sidebands and improves linearity for the entire signal chain.
I asked ADI about the competitive advantages of this new design, and here is what they pointed out:
Price and Availability
- Continuous operation from 700 MHz to 2800 MHz
- Best in class linearity and noise figure that is maintained across frequency band
- Input IP3 of 24 dBm; Noise figure of 11 dB SSB
- Power conversion gain of 7 dB
- Suitable for high performance wideband receivers for next generation communication systems
- LTE / WCDMA / CDMA / GSM
- Support industry trend of wideband radio platforms that support multiple bands and multiple standards.
- Best in class SFDR and blocker performance
Samples and evaluation boards are available, by 3Q 11 parts will be ready.
ADL5811, 32-pin LFCSP, $8.03 in 1,000 qty.
ADL5812, 40-pin LFCSP, $10.98 in 1,000 qty.
So, if you are in the market for a wideband mixer, this looks like a good option. For a closer look, head to the specs: