Driver amplifier design
In what way this driver amplifier operating near P1dB region design is different from a power amplifier design ! i am totally confused before starting the design!
Essentially you confuse "Power Amplifier Design" and "Linear Amplifier Design"..
For instance, an amplifier has -10dBm@P1dB Output Power, is it an "Power Amplifier" ? Definitely No..
Therefore you should inform firstly your target P1dB Output Power.Then, we may go further..
If you design the amplifier for operation in non-linear mode (P1dB), the design method for power amplifiers apply.
Dear sir,
In continuation to our earlier discussion earlier discussion, i just want to mention that output of the driver amplifier is connected to the LO port of the single balanced mixer(power required to drive the mixer~ 4.0dBm) and the driver amplifier has to operate in P1dB region so as to avoid any LO variations, we are using low noise /low power PHEMT( CFY67-08, ) for the amplifier design.
Can i follow gain match(s22 conjugate match in linear region) and then simply determine P1dB compression point! using the nonlinear model( as we dont want to extract full device power )
OR
We go power amplifier design method!
Can any one explain me clearly what is the difference between gain match and power match?
Q2)I have tested one amplifier recently according to the data sheet OIP3 is 44dBm and after testing iam getting OIP3 around 39dBm only i have played with the output matching network like i have degraded the output return loss then my OIP3 is getting around 43dBm
Q3)If i degrade the output matching network why my OIP3 is improved?
Q4)at the same time gain is little bit falling by 0.4dB and P1 dB also improved by 1dBm .why it happened like that?
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Can i use the technique(for the design of driver amplifier for low power--- basically requires to drive the mixer LO portthe requires~4dbm at p1dB) that plotting the power gain circles to find a value of gamma-L , then conjugate match the input for maximum output power ( of course by checking the i/p-o/p stability). all these will be done in linear region by generating s-parameters by the model at the specific bias point!. After that we will incorporate the device model with the input-output matching to predict p1dB. ( here i am planning for gain match instead of power match)
Plz reply as i am waiting for the valuable guidance prior to start the design!
Can power added efficiency(PAE) term is applicable for the driver amplifier. Suppose output power at the linear range is 3.0dBm with the input power of -2.0dBm how we will calculate the efficiency? is PAE applicable? PAE is applicable to linear range only!Plz help me to overcome all the queries!
Your amplifier works almost being as Linear Amplifier, not PA.. Therefore PAE is not a concern...
You should consider Conjugate Impedance Matching within this power levels.Maybe some tweaks are necessary but definitely not Power Matching.
OIP3 is dependent may factors as well as Matching Circuits, that's why when you modify this circuit, OIP3 will obviously be impacted.
I recommend you to implement application circuit which is dedicated to your application and frequency.Because the manufacturer knows the characteristics of their circuit better than you.
If you drive a Mixer with a constant drive level, I suggest you consider some different alternatives such as Cherry-Hooper amplifiers..
i have used a receiver module mini circuits mixer,
i am using a standard GALI amplifier for driving my LO,
I observed only a 1 dB variation in the output power after downconversion with 5dB LO variation but this was in the case of a 10dBm LO drive mixer.
i do not think compression the LO driver amplifier is required in higher LO drive cases , we can use it in a level safer below compression point .
Also when compressing the amplifier the harmonics generated by it a increased by 10 dB or so (But it did not affect my receiver performance).