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DRAFT: This document is still being modified by the author. Any information here is subject to change.

Calibration Process

In general, there are 5 source paths and 4 receive paths that must be calibrated. The cal process is a bootstrap process. The source must be calibrated enough to be used for the receive path cal, although not as a cal standard, but rather as a 'relatively close' uncalibrated source. After the source is made relatively close, the receive path can be cal'd against a power meter. Then the receiver can be used as a secondary standard to accurately cal the source paths. This entire process must be repeated for both PortRF1 and PortRF2.

All the cals are written based on using source1 for the 'src' path, source2 for the 'IM' path, and source3 for the 'Aux' path.

The validates are not listed here but each cal is accompanied by a validate.

RI8607A PortRF1 Src Freq Resp Prelim Cal Iterative

This is an initial cal that gets the portRF1 source power accurate at -3 dBm. This is solely for the purpose of getting a single, relatively accurate, source power to calibrate the receiver. The result does not have to be completely accurate, only close enough that the receiver will not be driven into compression or have to measure too close to the noise floor.

The measurements are done using a power meter at portRF1.

This is an iterative cal. It may have to be rune more than once for its validate to pass. On a brand new TIM, it might take 5 or more repeats to pass. On a previously cal'd TIM, it will only take 1 or 2 runs.

Each successive run should result in a lower maximum error. If not, something is wrong, and the cal will not converge.

One trick is to watch the power meter as this cal runs. If the most significant digit (the single units digit) ever shows anything but a 2 or 3 (indicating <-4 or >-2 dBm), then the cal will likely have to be run again.

The results of this cal will be thrown away when the source linearity cal is run. The linearity cal and the source frequency response cal replace this cal and provide accurate power at all frequencies/powers.

RI8607A PortRF1 Rcv Freq Resp Cal

This cal gets the portRF1 a1 receive path accurate. It compares the receive measurement to the power meter to calculate the cal data. As such, the source power needs to be somewhat close but does not need to be completely accurate.

The receive path, if not in compression and not too close to the noise floor, is linear, so this cal only needs to be done at one power.

RI8607A PortRF1 Src Linearity Cal

All of the source paths, through amps and doublers, have a non-linear transfer function. ie. the output power is not directly proportional to the input power. Additionally, the linearity curve varies with frequency.

This cal plan calibrates the portRF1 Src path for linearity. Because the linearity curve varies with frequency the cal plan must perform a significant number of power sweeps across frequency. It performs about 200 power sweeps, each with about 90 points for a total of about 17000 points. Consequently, this cal takes a long time to compile and run.

This cal uses the (just calibrated) receiver because the power meter does not have the dynamic range or speed to be used for this cal.

RI8607A PortRF1 Src Freq Resp Cal

This cal plan calibrates the portRF1 Src path for frequency response. The linearity cal has made the source path accurate at specific frequencies. This cal fills in the points between the linearity cal sweeps.

This cal uses the receiver to calibrate the source.

RI8607A PortRF1 IM Linearity Cal and RI8607A PortRF1 IM Freq Resp Cal

These cals are the same as the 'Src' path cals but using source2 through the IM path. The cals are adjusted to account for the fact that the IM path has approximately 6 dB less maximum output power.

RI8607A PortRF1 ea Cal

This is a classic ea cal, using an open/short/load to perform a complex VNA calibration on portRF1. The result is complex cal factors for directivity, port match, and reverse gain. Note that forward gain is always 1.

PortRF2 cals

PortRF2 runs identical cals to pPortRF1, with the exception that PortRF2 also has an Aux source path. So the following cals are also run:

RI8607A PortRF2 Aux Linearity Cal and RI8607A PortRF2 Aux Freq Resp Cal

These cals are the same as the other 'Src' path cals but using source3 through the Aux path. These cals expect an Anritsu signal generator, which is only 20 GHz. Hence, these cals are only run to 40 GHz. Additionally, the Aux path is not amplified in the TIM, so there is not quite as much power available at high frequency.

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