Guerrilla RF Newsletters

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How Do I Improve Gain Flatness Without Sacrificing Return Loss?

APRIL 13, 2018

Your broadband application requires a highly efficient, linear driver that features superior gain flatness with excellent return losses over the band. The return loss requirement prevents the use of mismatch at the low end of the band to flatten the gain, so what do you do?
Since the requirement is for a driver, the noise figure (NF) is typically not critical, so there is freedom to tweak the input matching to flatten the gain. Gain will be highest at the low end of the band, so the challenge becomes how to selectively reduce the low frequency gain more than the high frequency gain while maintaining good return losses.
A frequency selective resistive load on the device input will do just that. Below is an s-parameter screenshot of the GRF4003 LNA/Driver optimized for 400 to 1000 MHz, or a fractional bandwidth of about 85%.


As you can see, the output return loss is very good across the band, but the input return loss is only around -8.5 dB and the gain roll-off is almost 5 dB.

The evaluation board schematic shows the driver solution with a shunt RL added to the device input. This configuration selectively loads the low end of the band more than the high end, so it should enhance the gain flatness with an S(1,1) improvement as well. 

Below are the evaluation board results using the frequency selective resistive loading on the input. Notice how both the gain flatness and the input return losses are both improved significantly.


Had this been an LNA application instead of a transmit driver, the shunt RL network could have simply been placed on the output side of the device with no impact on the input-referenced linearity. Due to the high gain of the device, this resistive loading on the output would have resulted in essentially no noise figure degradation.

How Can I Get Low Noise And Good Matching?

MARCH 13, 2018

If your receiver lineup must have the lowest possible cascaded noise figure (NF), then Guerrilla RF’s GRF207X or GRF208X low noise amplifier (LNA) families will provide the ultra-low noise and high gain you need in a standard DFN-8 package and pinout.
One challenge with cascading ultra-low noise amplifiers with high Q filters is the impedance matching. To achieve optimal passband and out-of-band responses, these filters often need to be terminated with an impedance close to 50 ohms or, equivalently, with a return loss >15 dB.
Ultra-low noise LNAs are typically presented with standard matches in their data sheets that optimize NF at the expense of return loss. The architecture of these LNAs also dictates that changes to their input matches strongly affect their output matches, and vice-versa. Attempting to reactively match the output for better S(2,2) will tend to disturb the input match and may even make it worse. Fortunately, there is a simple way around this problem.
Resistive loading can be added to the output match. The resistance will improve the output return loss while allowing the input to be matched with a high Q reactive network for improved S(1,1) and optimal NF. The loading can take the form of either a shunt R, series R, or a resistive Pi or T pad.
To the right is an example of an improved return loss schematic for our ultra-low noise GRF2071. The high Q shunt L on the input side improves S(1,1) while the 500 Ohm resistor in parallel with the bias inductor increases S(2,2).
Negatives of this approach are that the device gain and output linearity are reduced by the loss of the resistor. For a high gain LNA, this resistive loss will have negligible impact on the noise figure. It should be noted that since the resistive loss occurs on the output side of the transistor, the input referenced linearity is relatively unaffected. An additional benefit of the resistive loading is that the stability margin of the amplifier is improved.
How much noise figure do we give up with this approach? For today’s ultra-low noise pHEMT LNAs, matching for a high input return loss of perhaps 20 dB with high Q inductors and capacitors will typically result in a noise figure penalty of less than 0.2 dB.

And You Thought the GRF2501 Was Impressive?

FEBRUARY 9, 2018

Guerrilla GRF2101 Image.gif

The GRF2501 is a world-class WLAN low noise amplifier, but there is a new product that extends our WLAN dominance - the GRF2101.

It offers higher gain, lower NF, better linearity andlower cost. The GRF2101 only requires 1 resistor to set the desired Iddq, and 3 capacitors to provide DC blocking, matching and bias de-coupling.

Take a look at the performance of the GRF2101. With the device biased at 3.3 V and 18 mA, noise figure and gain truly shine.

The GRF2101 is pin compatible with the GRF2501 in an industry-standard 1.5 x 1.5 mm DFN-6 plastic package.

Evaluation boards are available now! 

Questions? Contact us at

Surprised by Avago/Broadcom EOL? We've Got You Covered!

JANUARY 19, 2018

Have you been affected by Avago/Broadcom’s sweeping Obsolescence Notification? To help you, we've put together a comprehensive...

Suggested Replacements List

With potential replacements for over 100 different Avago products, we are ready to help you during this major transition!

Please contact us at for further assistance.


Need to Swap Out Amplifiers in a Common Footprint? No Problem!

JANUARY 10, 2018

With a single, compact layout, you now have access to a wide breadth of RF capability. Product obsolescence? System requirements change? Simply select a different component and move forward. In an ultra-small 1.5 mm DFN-6 package, Guerrilla RF offers a modular RF design system featuring almost 20 devices.

With a single footprint/pinout, you simply need to populate the components required by a particular device. These devices include single and multi-stage amplifiers with a wide variety of gain, NF, linearity, bypass capability and price points to give you ultimate design flexibility.

Flexible supply voltage and current allow for additional performance tradeoffs.


Broadband Gain Block to X-Band


Broadband Gain Block to X-Band


Broadband Gain Block to X-Band


Broadband Gain Block to X-Band


Flat Gain, High Linearity Gain Block


Broadband LNA/Linear Driver


Flat Gain, High Linearity Gain Block


Broadband LNA/High Linearity Driver


Flat Gain, High Linearity Gain Block


Broadband LNA/High Linearity Driver


Low NF, Low Current Amplifier


Broadband LNA/High Linearity Driver


Ultra-high Gain, Low NF Amplifier


Broadband LNA/High Linearity Driver


Low NF, Low Current Amplifier/Bypass 


High Gain, High Linearity, Low NF


Linear Driver/ LNA for C-Band/ 


Broadband LNA/High Linearity Driver/Bypass

In the coming months, we'll be adding several new 1.5mm DFN-6 devices, giving you even more options. Guerrilla RF remains committed to providing the high performance RF solutions you need, and we are pleased to provide the applications support you need to successfully implement any of our devices.

Please contact us at!

What Is the Quickest Way to Find Your Ideal Amplifier?

DECEMBER 8, 2017

At GRF, applications support is a core competency and focus. We provide detailed support for our customers from initial device selection through prototype evaluation and production ramp. For initial device selection, customer system requirements will determine the radio architecture and the performance goals for each radio section.

Guerrilla Amplifier Image.pngTo select the ideal amplifier device, all critical specs must be considered together. These include:

  • Application Bandwidth (Min and Max Frequency)
  • Gain
  • Gain Flatness and Associated Return Loss
  • Min OP1dB
  • Min OIP3
  • Max NF
  • Bypass Capability
  • Preferred/Available Supply Voltages
  • Max Iddq
  • Operating Temperature
  • Target Cost and Associated Estimated Annual Usage

If you want to find an amplifier as quickly as possible, then provide as many of the above requirements as possible when contacting our applications group. With this information, we can promptly recommend the ideal solution from our device portfolio.

An additional step you can take to expedite the process is rank the above parameters in order of relative importance. This ranking will allow us to manage the usual performance tradeoffs.

Our goal is to provide the most cost-effective, efficient solution that provides the required margin to all your key specifications. We look forward to assisting you with all your current and future design challenges!

Contact us at