I received news this week that Linear Technology had released the LTC554x family of high-dynamic-range downconverting mixers for 700MHz to 4GHz wireless infrastructure. The devices have been optimized for low power, operating from a single +3.3VDC supply. The company reports that this results in power consumption that is 34% less than the closest competition.

What I love about Linear Technology news releases is that they are always jam-packed with specs, and this one was no exception. Here's a table for you:

But, I still had some additional questions, and Tom Schiltz, RFIC Design Section Leader, Linear Technology Corporation was kind enough to fill me in on the missing details…

TechBites: Why did you choose the functions that you did to include on the chip?
Schiltz: The functions integrated on the chip include a passive mixer, LO switch, LO amplifier, IF amplifier and bias circuits with a shutdown mode. These functions were chosen to offer the highest system integration and the highest dynamic range.

TechBites: What off-chip components are required?
Schiltz: These mixers require only 11 low-cost passives (L, C & R) for supply decoupling and impedance matching, and a 4:1 impedance ratio transformer for the IF output.

TechBites: What technical challenges had to be overcome to develop this product? How did your design team overcome them?
Schiltz:

*Designing wideband, high output voltage LO amplifiers, while simultaneously reducing power consumption. Overcome by a clever low-voltage LO buffer design.
*Maintaining low noise figure under large-signal blocking conditions while using internal bias circuits. Overcome with a special, low-noise current reference design.
*Linearity (IIP3) simulation results for this mixer topology are unreliable. Overcome by using the design team’s 45+ years of combined RF experience to focus on other simulation results to estimate the mixer’s IIP3.

TechBites: What are its competitive advantages? (Obviously power consumption, anything else?)
Schiltz:

*        Very high dynamic range (IIP3 – Noise Figure), coupled with high conversion gain.
*        The lowest DC power consumption available in this dynamic range class of mixer.
*        Shutdown feature for system power savings.
*        Integrated bias circuits
*        LO inputs that are 50W matched, even when the IC is shutdown, to minimize VCO/PLL pulling.

If you want to know more about these new mixers, you can head on over to the Linear Technology website for the datasheet.

And, if you have an opinion on this new product, or have used it, please sound off below.