Intermodulation (IM) distortion and Second order intermodulation products or IP2 discussion. Second– and third-order product locations are shown in Figure 3-20. intermodulation products, particularly the third-order inter-modulation (IM3) products . For low level input signals, the IMD products remain relatively constant regardless of signal level. to produce a series of second order sum and difference products, third order products etc. Figure 7.24. This is shown in Figure 6-139 within the region where the ideal slope = 1 line becomes dotted, and the actual response exhibits compression (solid). Ben Duncan A.M.I.O.A., A.M.A.E.S., M.C.C.S, in High Performance Audio Power Amplifiers, 1996. The IM3 level was approximately 9 dB lower. TABLE 8.7. This value is then multiplied by 2 to yield 64 dB (the value of the third-order, Radio frequency power amplifier for wireless communication, Electrical Systems and Equipment (Third Edition), Application and optimization of a 2GHz differential amplifier/ADC driver, AEU - International Journal of Electronics and Communications, Reference Data for Engineers (Ninth Edition). Intermodulation is a scenario where signals outside the monitored channel combine nonlinearly to produce a frequency of monitored channel. Similarly, higher-order terms give rise to higher-order harmonic and intermodula-tion distortion. This characteristic is curved which, to the mathematically minded of you, will immediately imply a power law. In simple terms, a power law is a relationship which does not relate one set of values (the input voltage) to another (the output voltage) by a constant, which would yield a straight-line relationship – and incidentally a distortionless amplifier, but by a function which is made up of both constant and multiplication factor which is related to itself. These power level values are usually referenced to the output power of the device delivered to a matched load (usually, but not necessarily 50 Ω) expressed in dBm. the second term is the fundamental signal(s). If the original frequencies are in a similar band, the four above terms will be situated relatively far away and, thus, easy to eliminate (even with inexpensive filters). One of the possible sources of intermodulation has been referred to in Section 8.7.1 of this chapter. LTC6400-20 2-Tone 3rd Order Intermodulation Distortion. To be able to select five channels without any third order intermodulation products being produced, it is necessary to have 12 regularly spaced (e.g., 25 kHz spaced) channels available. But the second- and third-order intercept lines may be extended to intersect the extension of the output signal line. Last, the 7kHz ‘carrier’ and nearly all noise are strongly removed by a LPF, leaving just the products. Third-order intermodulation products are. Figure 6.3. For the power station UHF band of frequencies, the third order intermodulation free channels would be Channels 21A, 22, 23A, 26 and 27. Table 1 lists the test results. The same reasoning applies here; the second harmonic of fs/3 is 2 fs/3, and its alias occurs at fs− 2 fs/3 = fs/3. Intermodulation noise is due to the presence of the products of intermodulation. Cheng-Wei Pei, Adam Shou, in Analog Circuit Design, 2013. In amplifiers, it is a common practice to specify the third-order IMD products in terms of the third-order intercept point, as shown in Figure 6-139. Put a different way, not this: where Eo is output voltage and Ei is input voltage. A differential RF signal and a differential local oscillator (LO) signal are mixed by a mixer to demodulate the RF signal. Figure 4 shows a graphical comparison of IM2 and IM3 performance. The calculator calculates IMD (Intermodulation) products based on two fundamental frequencies. To determine the IP3 point, two spectrally pure tones are applied to the system. Intermodulation noise differs from thermal noise since it is a function of the signal power at the point of non-linearity. In Electrical Systems and Equipment (Third Edition), 1992. K2(VIN) 2 =K 2(E1 2sin2ω 1t+E2 2sin2ω 2t+ 2E1E2sin 2ω 1t(sinω2t)) (1) (2) (3) (4) (5c) (5a) (5b) Term (a) from Equation 7 represents amplitude offset at the fundamental frequencies. Nevertheless, both the second- and third-order intercept lines may be extended, to intersect the (dotted) extension of the ideal output signal line. To achieve reasonably accurate results at least the first five orders (even and odd) of IM products must be measured. The most prevalent source of interference is intermodulation products which can be produced in any non-linear impedance, given the right conditions. Slew-induced distortion (SID) can produce intermodulation distortion (IMD) when the first signal is slewing (changing voltage) at the limit of the amplifier's power bandwidth product. For a given frequency, knowing the third-order intercept point allows calculation of the approximate level of the third-order IMD products as a function of output signal level. Figure 1 shows the intermodulation spectrum resulting from two signals and the formulas for determining the resulting frequency components. Intermodulation distortion comes about due to the presence of non-linearities in an electronic system as well.1 Take for instance the triode transfer characteristic illustrated in Figure 4.1. Degree in electrical engineering in 1987 from Fachhochschule Augsburg. Unless otherwise specified, two-tone IMD refers to these third-order products. Therefore, the self-intermodulation of the test bench is displayed as a result. The second IMD can be found by analyzing the third term of Equation 3. Unlike traditional “open-loop” RF/IF amplifiers, where there is very little or no feedback used in the amplifier circuit, the LTC6400 contains an internal differential op amp with the gain set using a feedback network. The smaller bandwidth is equal to the bandwidth of the adjacent channel signal. The second order intermodulation product (the sum frequency) is at 14.165. When the input signal is within a few dB of the ADC FSR, the IMD may start to increase (but it might not in a very well-designed ADC). A variety of attempts to reduce or eliminate intermodulation have been carried out and are reported in this article. But due to the superior discrimination against noise, in having a bandwidth of about 700Hz, it can yield a % distortion figure that is x2 (6dB) to x3 (10dB) lower, and closer to real %THD, assuming the associated %THD+N measurement is mainly noise-laden due to a 22kHz or greater bandwidth. Once the loop gain begins to roll off at higher frequencies, the distortion performance begins to suffer. The logarithm of the products of the rows for the transmission characteristic and the IM products provides the power levels of IM2 and IM3, depending on the included orders in the transmission characteristics. The order of the intermodulation product depends on how many input signals are mixed and which harmonics of each of those input signals have mixed. For most analogue systems with many multiplexed channels, the addition of the very large combination of signals results in an output noise spectrum which is approximately flat with a frequency across a narrow band of about 4kHz. But in all cases, the intermod products caused are close to the HF tone and are liable to be masked. Intercept points for data converters have no practical significance. The questions of what power level the second-order IM product appears at and whether there is any relationship between the levels of other-order IM products is analyzed from a theoretical standpoint. The test usually comprises a low frequency. The second-order intermodulation products correspond to (⍵1 ∓ ⍵2) terms. 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