The phase control in these ADCs may be performed on the internal oscillator. As we have seen with fiber optic links, wireless links, and any other modern data standard, it is easier and cheaper to use millions of transistors to digitally compensate for a bad signal than to create the analog channel necessary for a good signal. Now that we have established that IF or LO amplitude and phase errors can be compensated, let us discuss the various ways in which this can be accomplished. It may be possible to show that any error in A or B can be compensated with phase terms, but we will not show that here. The problem, however, is that this cannot be done in a convenient way. Any deterministic impairment can be pre- or post-compensated, and sideband suppression is definitely deterministic.

It may be possible to show that any error in A or B can be compensated with phase terms, but we will not show that here. In the chart above sideband suppression is increased from about 19 dB to 23 dB by adding an offset voltage, and then again to 50 dB or so by combining phase manipulation with the DC offset. For more information consult the usually very detailed datasheet of a dual channel high speed ADC. If the IQ mixer is built as a bolt-together solution, then the phase can be manipulated by varying line lengths or with a phase trimmer. In MLIQ mixers in chip form, the LO phase can be trimmed by applying ceramic, absorber, or other microwave tuning elements familiar to the microwave black magicians out there to the LO quad hybrid in a certain way while observing the sideband suppression. Since some of this is proprietary I will leave it at that and say that you should contact support at Marki for more information. This makes them readily accessible for IF amplitude and phase manipulation.

In this blog post we will examine various ways to compensate for the fact that these structures are built with real components with imperfect phase and amplitude balance. This makes them readily accessible for IF amplitude and phase manipulation. This technique can be used without penalty for image reject mixers, however, since the LO is out of band of the IF output. This has the profound implication that by correcting the phase of the LO signal driving the receiver side mixer, we can compensate for any imperfections in the transmitting side mixer.

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It may be possible to show that any error in A or B can be compensated with phase terms, but we will not show that here. The IQ mixer is the backbone of modern communications architectures, as well as advanced vector signal analyzers for electronic warfare and test and measurement receivers.

In the chart above sideband suppression is increased from about 19 dB to 23 dB by adding an offset voltage, and then again to 50 dB or so by combining phase manipulation with the DC offset. Now that we have established that IF or LO amplitude and phase errors can be compensated, let us discuss the various ways in which this can be accomplished.

5 Ways to Compensate for Passive IQ Mixer Imbalance – Marki Microwave RF & Microwave

If the IQ mixer is integrated, however, it is more difficult. In this blog post we will not address compensation for spurs, although this is possible. For more information consult the usually very detailed datasheet of a dual channel high speed ADC. Specifically, two of the diodes will turn on at a higher voltage, and two of them will turn off at a higher voltage. Without phase compensation the possible improvements can be severely limited, depending on how close the theesis balance is to start with.

Any deterministic impairment can be pre- or post-compensated, and sideband suppression is definitely deterministic. The phase control in these ADCs may be performed on the internal oscillator.

Amplitude and offset correction registers are generally built into DACs that are designed for communications, arbitrary waveform generation, and software defined radio applications. If we control the LO but not the IF, then an amplitude error is more serious, since it causes the C 3 constant to not cancel.

upconversion mixer thesis

The output is given by the sum of the top two terms, where the first is the desired sideband low upconvversion in this case and the second term is the undesired or suppressed sideband. This is the big daddy when it comes to analog IQ compensation methods. As we have seen with fiber optic links, wireless links, upcovnersion any other modern data standard, it is easier and cheaper to use millions of transistors to digitally compensate for a bad signal than to create the analog channel necessary for a good signal.

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5 Ways to Compensate for Passive IQ Mixer Imbalance

There are myriad methods to perform this digital compensation, with different cost tradeoffs. The phase can also be manipulated in digital implementations. The constants in front of the two terms show the magnitude of the conversion loss ideally and the sideband suppression.

upconversion mixer thesis

Since some of this is proprietary I will leave it at that and say that you should contact support at Marki for more information. First we need to answer the question, can IQ imbalance be compensated? The ipconversion basic approach for sideband suppression is to simply receive both I and Q channels, and estimate the distortion ,ixer from the Q channel in the I channel, and subtract your received estimate of the Q channel from the I channel.

This is the ultimate in IQ compensation techniques.

The application of a DC voltage to the IF port of a double balanced mixer will change the bias conditions of the diode rings inside. The problem, however, is that this cannot be done in a convenient way. As you can see the application of a DC voltage will degrade the conversion loss without changing the phase, allowing you to easily vary the amplitude balance of one side of an IQ mixer.

Here we are performing a single sideband upconversion where the desired sideband signal is corrupted by LO feedthrough, the suppressed sideband, and spurious products.

upconversion mixer thesis

The penalty, as you can see, is an increase in the LO feedthrough from dBm to -3 dBm, overpowering even the desired sideband. In MLIQ mixers in chip form, the LO phase can be trimmed by applying ceramic, absorber, or other microwave tuning elements familiar to the microwave black magicians out there to the LO quad hybrid in thezis certain way while observing the sideband suppression.

The latter term goes to 0 with perfect error terms, while the former goes to 1. There are easily references for this topic, including several books, and most are full of dense math and advanced digital signal processing. Unfortunately there is a tradeoff.